Projection apparatus and control method

ABSTRACT

A projection apparatus executes a first processing and a second processing on image signal received from an external device, projects an image based on the image signal processed by an image processor, and switches an operation mode of the projection apparatus to a first mode, which is a low-latency mode for suppressing a delay in displaying an image, and a second mode, which is not the low-latency mode. The image processor maintains the first processing and stops the second processing in response that the operation mode of the projection apparatus is switched to the first mode from a state in which the operation mode is the second mode and the first processing and the second processing are executed.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a control technique for a projectionapparatus capable of switching between a low-latency mode and ahigh-quality mode.

Description of the Related Art

Recently, a low-latency of display processing is required for the imagedisplay device used in esports (electronic sport) or the like. For thisreason, some recent display devices are equipped with a function thatallows switching between a low-latency mode and a high-quality mode inthe image display device in conjunction with an image output device suchas a video game or a PC (Personal Computer).

WO 2014/141425 discloses a technique for realizing a low-latency ofdisplay processing in a TV by reducing the burden on the displayprocessing by thinning out the image processing when operation mode ofthe TV is set to the game mode, thereby realizing a low-latency.

In order to realize low-latency in a projection apparatus such as aprojector by the method described in WO 2014/141425, image processingperformed by the projection apparatus needs to be thinned out. In theprojection apparatus, in addition to the image quality enhancementprocessing such as noise cancellation, image processing for correcting adeformation, a rotation and an inversion caused by an installationcondition of the projection apparatus, such as a keystone correction, awarping correction and a vertical and horizontal inversion correction,is performed.

However, if the image processing for correcting the above deformation,rotation, and inversion when the transition to the low-latency mode inthe projection apparatus is thinned out, there is a possibility that aviewability of the projection image will be significantly decreased.Therefore, when the projection apparatus transits to the low-latencymode, it is necessary to reduce the processing load regarding the imageprocessing and to appropriately control to suppress the decrease in theviewability of the projection image.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of theaforementioned problems, and realizes techniques for performingappropriate control to reduce the processing load on the imageprocessing when the projection apparatus transits to the low-latencymode, thereby suppressing the decrease in the viewability of theprojection image.

In order to solve the aforementioned problems, the present inventionprovides a projection apparatus comprising: a communication unitconfigured to communicate with an external device; an image processorcapable of executing a first processing including at least one of adeformation, a rotation and an inversion, and a second processing otherthan the first processing, on image signal received from the externaldevice via the communication unit; a projection unit configured toproject an image based on the image signal processed by the imageprocessor; and a control unit configured to switch an operation mode ofthe projection apparatus to one of a plurality of operation modesincluding a first mode, which is a low-latency mode for suppressing adelay in displaying an image, and a second mode, which is not thelow-latency mode, wherein the image processor maintains the firstprocessing and stops the second processing in response that theoperation mode of the projection apparatus is switched to the first modefrom a state in which the operation mode of the projection apparatus isthe second mode and the first processing and the second processing areexecuted.

In order to solve the aforementioned problems, the present inventionprovides a method of controlling a projection apparatus whichcommunicates with an external device, comprising: executing imageprocessing including a first processing including at least one of adeformation, a rotation and an inversion, and a second image processingother than the first processing, on the image signal received from theexternal device; projecting an image based on the image signal on whichthe image processing has been executed; and switching an operation modeof the projection apparatus to one of a plurality of operation modesincluding a first mode, which is a low-latency mode for suppressing adelay of an image display, and a second mode, which is not thelow-latency mode, wherein in the image processing, the first processingis maintained and the second processing is stopped in response that theoperation mode of the projection apparatus is switched to the first modefrom a state in which the operation mode of the projection apparatus isthe second mode and the first processing and the second processing areexecuted.

In order to solve the aforementioned problems, the present inventionprovides a non-transitory computer-readable storage medium storing aprogram that causes a computer to execute a method of controlling aprojection apparatus which communicates with an external device,comprising: executing image processing including a first processingincluding at least one of a deformation, a rotation and an inversion,and a second image processing other than the first processing, on theimage signal received from the external device; projecting an imagebased on the image signal on which the image processing has beenexecuted; and switching an operation mode of the projection apparatus toone of a plurality of operation modes including a first mode, which is alow-latency mode for suppressing a delay of an image display, and asecond mode, which is not the low-latency mode, wherein in the imageprocessing, the first processing is maintained and the second processingis stopped in response that the operation mode of the projectionapparatus is switched to the first mode from a state in which theoperation mode of the projection apparatus is the second mode and thefirst processing and the second processing are executed.

According to the present invention, when the projection apparatustransits to the low-latency mode, an appropriate control for reducingthe processing load on the image processing can be performed to suppressthe decrease in the viewability of the projection image.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments (with reference to theattached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a system in which a projector and a PCare connected;

FIG. 2A is a block diagram illustrating the configuration of theprojector.

FIG. 2B is a block diagram illustrating the configuration of the PC.

FIG. 3A is a flowchart illustrating image display processing by theprojector.

FIG. 3B is a flowchart illustrating image output processing by the PC.

FIG. 4A is a flowchart illustrating processing by the PC in alow-latency mode.

FIG. 4B is a flowchart illustrating processing by the projector in thelow-latency mode.

FIG. 5 is a flowchart illustrating processing by the projector in thelow-latency mode of a first embodiment.

FIG. 6A is a diagram illustrating a UI (User Interface) screen forsetting operation modes according to the first embodiment;

FIG. 6B is a diagram illustrating a UI screen for geometric deformationsetting of the first embodiment.

FIG. 7 is a flowchart illustrating processing by the projector in thelow-latency mode according to a second embodiment.

FIG. 8A is a diagram illustrating an OSD for vertical and horizontalkeystone setting according to the second embodiment.

FIG. 8B is a diagram illustrating an OSD for simple warping settingaccording to the second embodiment.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments will be described in detail with reference tothe attached drawings. Note, the following embodiments are not intendedto limit the scope of the claimed invention. Multiple features aredescribed in the embodiments, but limitation is not made an inventionthat requires all such features, and multiple such features may becombined as appropriate. Furthermore, in the attached drawings, the samereference numerals are given to the same or similar configurations, andredundant description thereof is omitted.

First Embodiment

In the present embodiment, an example in which a projector and a PC areused as an image display apparatus and an image output apparatus,respectively, will be described.

FIG. 1 illustrates an example in which a projector 100 and a PC 200 areconnected to each other, an image signal output from the PC 200 isreceived by the projector 100, and the projector 100 displays aprojection image 300 on a screen 400. The PC 200 is a Source device thatoutputs image signal to the projector 100 as a Sink device that displaysimages.

The projector 100 has an image input unit 110, which will be describedlater in FIG. 2A, and is connected to the PC 200 via an interface cable500 such as a HDMI® (High-Definition Multimedia Interface cable. The PC200 has an image output unit 206, which will be described later in FIG.2B, and is connected to the image input unit 110 of the projector 100via the interface cables 500.

A projection image 300 is an image which is output from the PC 200 tothe projector 100, and is projected on the screen400 by performingvarious image processing by the projector 100.

The PC 200 can transmit a transition instruction to the low-latency mode(a first mode) or the high-quality mode (a second mode), to theprojector 100. The projector 100 can be switched to the low-latency modeor the high-quality mode in response to an operation mode transitioninstruction from the PC 200. The low-latency mode is a mode forsuppressing a delay in an image display of a video game or the like.

The configuration and functions of the projector 100 and the PC 200 willbe described below.

First, the configuration and function of the projector 100 will bedescribed with reference to FIG. 2A.

A control unit 101 includes a microcomputer including a CPU, an I/Ocircuit, an internal register, etc., and controls the respective blocksof the projector 100. The control unit 101 is connected to each blockvia a bus 133, and can exchange various signal and data with each block.

An operation unit 102 includes, for example, switches, dials, and atouch panel provided on a display unit 128 described below, and acceptsuser operations and transmits an operation signal to the control unit101. Moreover, the operation unit 102 may include a signal receiver (forexample, an infrared receiver 122 described below) that receives anoperation signal transmitted from, for example, a remote controller (notillustrated), and output the received operation signal to the controlunit 101. Furthermore, the control unit 101 receives operation signalinput via the operation unit 102 and a USB interface 112 described belowand control signal input from a communication unit 114, so as to controleach operating block of the projector 100.

A power supply unit 103 controls the supply of power to each block ofthe projector 100.

A liquid crystal unit 104 includes one liquid crystal panel, threeliquid crystal panels, or the like, and forms images on the liquidcrystal panels.

A liquid-crystal control unit 105 controls, based on an input imagesignal, the voltage to be applied to each pixel of the liquid crystalpanels of the liquid crystal unit 104 so as to adjust the transmittanceof light, and forms an image on the liquid crystal panel. A light source106 outputs light to the liquid crystal unit 104, and is, for example, ahalogen lamp, a xenon lamp, a high-pressure mercury lamp, an LED lightsource, a laser diode, or a type of light source that uses a phosphor orthe like to excite light emitted from a laser diode so as to convert thelight wavelength.

A projection optical system 107 projects, onto the screen 400, an imageformed on the liquid crystal panel of the liquid crystal unit 104. Theprojection optical system 107 includes a plurality of lenses andactuators for driving the lenses. By driving the lenses using theactuators, enlargement, reduction, shift, focus adjustment, etc., of theprojection image can be performed.

A light-source control unit 108 controls the on/off and the lightintensity of the light source 106.

An optical-system control unit 109 performs zooming, focus adjustment,and/or the like by controlling the actuators of the projection opticalsystem 107.

An image input unit 110 can be connected to an external device such asthe PC 200 via the interface cable 500 shown in FIG. 1 , and receivesdigital image signal from the connected device. The image input unit 110is, for example, an HDMI®, and can receive image signal, audio signal,metadata and control signal according to protocol complying with HDMI®.Moreover, when an analog image signal is received, the image input unit110 converts the received analog image signal to a digital image signaland transmits the digital image signal to an image processor 116. Thatis, the image input unit 110 has a function of converting an analogimage signal to a signal receivable by the image processor 116 describedbelow, and further has a function of acquiring metadata superimposed(attached) on an image signal, a function of measuring the framerate(signal timing) of an image signal, and the like. An image output deviceas the external device is not limited to the PC 200 or the like, and maybe a camera, a mobile phone, a smart phone, a hard disc recorder, a gameconsole, or the like, as long as it can output image signal.

The image input unit 110 has a built-in storage unit (not illustrated)for storing Extended Display Identification Data (EDID) and the like.Moreover, the storage unit (not illustrated) stores video formatinformation that can be received, signal transmission rates, othercorrespondence information to optional functions, information based on apredetermined format, and the like.

The EDID can be read/written based on an instruction from the controlunit 101. When the EDID is read/written by the PC 200, the EDID isaccessed via an auxiliary communication channel called DDC (Display DataChannel) of HDMI® cable which is the interface cable 500 (hereinafter,DDC-line).

The image signal input from the image input unit 110 is directly outputto the image processor 116.

A universal serial bus (USB) interface 112 is an interface that accessesa memory device, which is a USB device, to read images, audio, and otherdata, and controls writing. Moreover, the USB interface 112 is aninterface that accepts an operation signal input via a pointing deviceor a keyboard, which is a USB device.

A memory card interface 113 accesses a storage medium, such as a memorycard, reads images, audio, and other data, and controls writing. Amemory card is a memory device, such as an SD card or a CompactFlash.For example, a document file input via the memory card interface 113 isreproduced by a reproduction unit 121 which will be described later. Thereproduction unit 121 generates image signal to be presented to the userfrom the document files, and outputs the image signal to the imageprocessor 116.

A communication unit 114 can receive various signal and data from anexternal device via an intranet, an Internet, or the like. Thecommunication unit 114 may be, for example, a wireless LAN, a wired LAN,a USB, Bluetooth®, or the like, and the communication method is notparticularly limited.

An internal memory 115 is a non-volatile semiconductor memory, a harddisc, or the like that stores images, audio, and other data.

The image processor 116 performs, on an image signal received from theimage input unit 110 and an image signal decoded by a replay unit 121described below, processing for modifying the frame number, the pixelnumber, the image shape, etc., and processing for superimposing anon-screen display (OSD), and outputs processed signal to theliquid-crystal control unit 105. The image processor 116, for example,converts the pixel number of an image signal according to the pixelnumber of the liquid crystal panel, and multiplies the framerate of theinput image signal and performs correction appropriate for imageformation performed by the liquid crystal panel, which is driven by analternate current (AC). Note that AC driving of the liquid crystal panelrefers to a method of alternating the direction of the voltage to beapplied to the pixels of the liquid crystal panel and displaying animage by using the property of the liquid crystal panel that an imagecan be generated when a voltage is applied in either the forward or thereverse direction. In such a case, the liquid-crystal control unit 105needs to transmit one of each of a forward direction image and a reversedirection image, and thus, the image processor 116 performs processingto speed up the framerate of the image signal. Note that the liquidcrystal unit 104 may be driven by the liquid-crystal control unit 105according to any method that corresponds with the applied voltage, suchas a drive method using an analog signal, a drive method using a digitalsignal according to pulse width modulation (PWM), or the like.Furthermore, in the case where a liquid crystal panel driven accordingto digital signal is used, a technique for reducing image qualitydegradation, such as a disclination caused by the driving method isused. Therefore, even when the liquid crystal panel is driven accordingto digital signal, the framerate may be multiplied.

Furthermore, the image processor 116 also performs a keystone (barrelshaped) correction when an image is projected onto the screen 400 at anoblique angle and the projection image is distorted, for example, into atrapezoidal shape, so as to modify the shape of the projection image sothat the trapezoidal distortion is cancelled out. When the keystonecorrection is performed, the enlargement/reduction ratio of the imagedisplayed on the liquid crystal panel is changed in the horizontaland/or vertical direction. In this way, the trapezoidal distortion ofthe projection image and the distortion in the image region on theliquid crystal panel are cancelled out, and an image having an aspectratio similar to that of a rectangular display region is displayed onthe screen 400. The keystone correction may operate automatically or maybe operated in response to an operation made by the user on theoperation unit 102, based on the incline angle acquired by an inclinedetector 117 described below.

Furthermore, the image processor 116 can also perform warping (yarnwinding shape) correction that is a kind of geometric deformation forcanceling the distortion when projecting with respect to a non-planesuch as a cylinder or a sphere. In addition, the image processor 116also includes a vertical inversion correction function for canceling asituation in which the projection image is also upside down when theprojector 100 is installed in the ceiling mounted in the verticalinversion, and a left-right inversion correction function for cancelinga situation in which the projection image is horizontally inverted whenthe projection image is rear-projected. These correction functions areappropriately implemented based on an instruction from the useroperation on the OSD menu or a detection result of the inclinationdetection unit 117 or an image capture result of the image capturingunit 124, which will be described later.

The inclination detection unit 117 detects the inclination of theprojector 100.

A timer 118 measures the operating time of the projector 100, theoperating time of each block, and the like.

A temperature detector 119 measures the temperature of the light source106 of the projector, the temperature of the liquid crystal unit 104,the ambient temperature, and the like.

A cooling unit 120 includes a heat sink, a fan, and the like for coolingby discharging the internal heat of the projector 100 to the outside.

The reproduction unit 121 decodes an encoded file or the like under thecontrol of the control unit 101, and outputs the decoded file or thelike to the image processor 116.

The infrared receiver 122 receives infrared light from a remotecontroller provided for the projector 100 or other devices, and outputsan operation signal to the control unit 101. A plurality of the infraredreceivers 122 may be disposed at a plurality of positions, such as thefront face and the rear face of the projector 100.

A focus detector 123 detects the distance between the projector 100 andthe screen 400 and detects the focal length of an image.

An image capturing unit 124 captures an image of the image projected viathe projection optical system 107 (in the direction of the screen 400)and outputs the captured image to the control unit 101. The imagecapturing unit 124 includes a lens group including a zoom lens and afocus lens for forming an optical image of a subject, an actuator thatdrives the lens group, and a microprocessor that controls the actuator.The image capturing unit 124 further includes an image capturingelement, such as a CCD, a CMOS, or the like that converts the subjectimage formed by the lens group to an electric signal, an A/D converterthat converts the analog signal acquired by the image capturing elementto a digital signal, and the like.

A screen photometry unit 125 measures the intensity and luminance of thelight reflected off the screen 400.

A display unit 128 is a display device formed of liquid crystal, organicEL, or the like, and is disposed in the projector 100 and displays theoperating state of the projector 100, a UI screen, warnings, etc.

A display control unit 129 controls the display unit 128 under thecontrol of the control unit 101.

A battery 130 supplies electrical power when the projector 100 is usedat a location where a power outlet or the like is not provided.

A power input unit 131 accepts AC power from an external power source140, such as an AC 100V source, rectifies the power to a predeterminedvoltage, and supplies the rectified power to the power supply unit 103.

A RAM 132 is used for loading programs stored in the internal memory 115and for temporarily storing various data and frame data of the image tobe projected.

Here, the term “programs” refers to programs for executing variousflowcharts as described below.

The bus 133 connects the control unit 101 and each block and exchangesvarious signal and data with each block.

Configuration of PC 200

Next, the configurations and function of the PC 200 will be describedwith reference to FIG. 2B.

A control unit 201 includes a microcomputer including a CPU, an I/Ocircuit, an internal register, etc., and controls each block of the PC200. The control unit 201 is connected to each block via a bus (notillustrated) and can exchange various signal and data with each block.

A media interface 202 is an interface that controls the reading andwriting of images, audio, and other data from and to an optical disc,such as a DVD.

An operation unit 203 includes, for example, a switch, a dial, a touchpanel provided on a display unit (not illustrated), and the like,accepts user operations, and transmits an operation signal to thecontrol unit 201. The control unit 201 receives operation signal inputfrom the operation unit 203 and a USB interface 208 described below andcontrol signal input from a communication unit 207, and controls eachblock of the PC 200.

A power supply unit 204 controls the power supply to each block of thePC 200. A power input unit 205 accepts AC power from an external device,rectifies the power to a predetermined voltage, and supplies therectified power to the power supply unit 204.

An image output unit 206 can be connected to an external device such asthe projector 100 via the interface cable 500 shown in FIG. 1 , andtransmits digital image signal to the connected external device. Theimage output unit 206 can transmit image signal, audio signal, metadata,and control signal according to protocol complying with HDMI®. Theexternal device is not limited to the image display device such as theprojector 100, and may be a recording device, a hard disk, a gamemachine, or the like.

A communication unit 207 can transmit and receive various signal anddata to and from the external device via an intranet, an Internet, orthe like. The communication unit 207 is, for example, a wireless LAN, awired LAN, a USB, Bluetooth®, and the like. However, the communicationmethod of the communication unit 207 is not particularly limited.

A USB interface 208 is an interface that accesses a memory device, whichis a USB device, and controls the reading and writing of images, audio,and other data. Moreover, the USB interface 208 accepts operation signalinput via a pointing device and a keyboard, which are USB devices.

A RAM 209 is used for loading programs stored in a storage device 210described below and for temporarily storing various data items and imageframe data. Here, the term “programs” refers to programs for executingvarious flowcharts as described below.

The storage device 210 is a nonvolatile semiconductor memory, a harddisc, or the like, and stores an operating system (OS), programs,various data items, such as content including text data and image data.

Based on an instruction from the control unit 201, an image processor211 performs various image processing on the image data stored in thestorage device 210 using the RAM 209 as a frame memory, and outputs theimage signal to the image output unit 206.

Next, operation when the PC 200 and the projector 100 transit to thelow-latency mode in conjunction with each other at the time ofdisplaying the image by the projector 100 and outputting the image bythe PC 200 will be described.

Image Display Processing

First, processing in which the projector 100 is connected to the PC 200,and receives and displays the image signal will be described withreference to FIG. 3 .

Hereinafter, a basic operation until the projector 100 is connected tothe PC 200, and receives and displays the image will be described.

In the present embodiment, it is assumed that the projector 100 and thePC 200 are connected by the HDMI® cable, image signal is output from thePC 200 according to protocol complying with HDMI®, and an image isdisplayed by the projector 100.

FIG. 3A illustrates processing performed by the projector 100, and FIG.3B illustrates processing performed by the PC 200. Note that theprocessing in FIG. 3A is realized by the control unit 101 executing aprogram stored in the internal memory 115 and controlling each block.Furthermore, the processing in FIG. 3B is realized by the control unit201 executing a program stored in the storage device 210 and controllingeach block. Moreover, the processing in FIG. 3B starts when a useractivates an application through a menu screen or the like of the PC200. Moreover, the processing in FIG. 3A starts when an instruction froma user for starting image display processing by the projector 100 isaccepted via a remote controller (not illustrated) or the operation unit102. The same applies to FIG. 4 which will be described later.

First, the operation of the projector 100 will be described withreference to FIG. 3A.

In step S301, the control unit 101, the PC 200 and the HDMI® cable bydetect that the power supply of 5V is output through the 5V power lineof the HDMI® cable from the PC 200, detect the connection with the PC200 by the HDMI® cable.

In step S302, the control unit 101 asserts HotPlugDetect (HPD) signalvia one line of the HDMI® cable, and notifies the PC 200 of the factthat the projector 100 is connected to the PC 200. The PC 200 havingreceived the HPD signal notification requests the projector 100 to readthe EDID via the DDC-line of the HDMI® cable.

In step S303, when the image input unit 110 receives the request forreading the EDID from the PC 200, the control unit 101 reads the EDIDinside, and notifies the PC 200 of the read result via the DDC-line. ThePC 200 reads the EDID from the projector 100 and subsequently requests atransmission of the image signal via the DDC-line.

Based on the EDID read from the projector 100, the PC 200 determines thenumber of lanes and the transmission rate in accordance with a videoformat to be transmitted, such as resolution, frame rate, and bit-depth,and transmits the image signal.

In step S304, when the image input unit 110 receives the image signalfrom the PC 200, the control unit 101 outputs the image signal to theimage processor 116, and the image processor 116 decodes signal data,converts signal, and measures an image signal timing.

In step S305, the control unit 101 reads various metadata such as videoformat data from the signal data decoded by the image processor 116, andwrites the metadata to a register held in the control unit 101.

In step S306, the control unit 101 performs processing such ascorrection for superimposing the OSD image on the image signal receivedfrom the PC 200 by the image processor 116 and converting the OSD imageinto a resolution suitable for displaying by the liquid crystal unit104, keystone correction based on the user setting, warping correction,vertical and horizontal inversion correction, and/or the like.

Image signal of a predetermined format is output from the image inputunit 110 through the above described processing, the image is formed onthe liquid crystal unit 104 through the image processor 116 and theliquid-crystal control unit 105 and is projected by the projectionoptical system 107 using the light source 106 in step S307.

Next, the operation of the PC 200 will be described with reference toFIG. 3B.

In step S311, when the control unit 201 is connected to the projector100 using the HDMI® cable, the image output unit 206 supplies power of5V via the 5V power line of the HDMI® cable.

When the control unit 201 determines that the image output unit 206detects that Hot Plug Detect (HPD) has been asserted via the HPD line inthe HDMI® cable in step S312, the control unit 201 requests the EDID viathe DDC-line and reads the EDID in step S313.

In step S314, the control unit 201 determines the format of the imagesignal to be output based on the content of the EDID read by the imageoutput unit 206, and transmits the image signal to the projector 100 viathe DDC-line.

According to the above described operations of the projector 100 and thePC 200, the projection of the image by the projector 100 is performed.

Operation 1 When Transition to Low-Latency Mode

Next, the operation 1 of the projector 100 and the PC 200 when atransition instruction to the low-latency mode is output from the PC 200to the projector 100 during projecting the image by the projector 100,will be described with reference to FIGS. 4A and 4B.

FIG. 4A illustrates processing performed by the PC 200, and FIG. 4Billustrates processing performed by the projector 100.

First, the operation of the PC 200 will be described with reference toFIG. 4A.

Communication processing between the PC 200 and the projector 100 isperformed according to protocol complying with HDMI®.

When the predetermined condition is satisfied, the PC 200 transmits atransition instruction to the low-latency mode to the projector 100. Thepredetermined condition is, for example, the moment at the start of agame application for which a delay reduction is required, or the momentat the transmission of the screen for the application for performing atouch operation on a projection surface, or the like.

In the present embodiment, an example in which a game application isexecuted and started by a user will be described.

In step S401, the control unit 201 starts executing the game applicationin response to a user operation.

In step S402, the control unit 201 causes the image output unit 206 torequest the EDID from the projector 100, read the EDID, and write theread EDID to the RAM209.

In step S403, the control unit 201 reads information indicating thedisplay capability of the projector 100, and determines whether or notthe transition to the low-latency mode is possible, or whether or not anoperation in the low-latency mode is possible, based on the information.The information indicating the display capability is stored as one-bitdata in a predetermined location in the EDID of the projector 100.

Although the EDID reading processing is performed in step S402 timing inthe present embodiment, the present embodiment is not limited to thistiming, and the EDID reading may be performed at the timing when theprojector 100 and the PC 200 are connected or at the timing when thede-assertion/assertion of the HPD is detected. However, since it isassumed that the EDID is dynamically rewritten without the control ofthe HPD when the projector 100 changes the operation mode by the useroperation, in the present embodiment, the EDID is read at the timing instep S402 that is the start of the mode transition processing.

In step S403, when the control unit 201 determines that the projector100 can transit to the low-latency mode or operate in the low-latencymode, the processing proceeds to step S404, and when the control unit201 determines that the projector 100 cannot transit to the low-latencymode or operate in the low-latency mode, the processing proceeds to stepS405.

In step S404, the control unit 201 transmits a low-latency modetransition instruction to the projector 100 by the image output unit206.

In step S405, the control unit 201 starts transmitting the video gamesignal via the DDC-line by the image output unit 206.

Next, operation of the projector 100 will be described with reference toFIG. 4B.

FIG. 4B illustrates processing after the low-latency mode transitioninstruction transmitted from the PC 200 in step S404 of FIG. 4A isreceived.

In step S411, the control unit 101 receives the low-latency modetransition instruction from the PC 200 through the image input unit 110.When the control unit 101 detects that the low-latency mode transitioninstruction has been received by interrupting or polling, the processingproceeds to step S412.

In step S412, the control unit 101 issues an instruction to the imageprocessor 116 to stop the various image processing that cause the delayand is applied to the projector 100. The image processing that causesthe delay is, for example, a deformation correction such as a keystone,a warping, a correction such as inversion and a rotation, an I/Pconversion or a super-resolution conversion to be predicted based on thefront and rear frames, reduction processing to reduce various noises,and/or the like. When these image processing is stopped, the processingproceeds to step S413, the image input unit 110 receives the video gamesignal, and the projection of the image is started.

According to the above-described processing, when the projector 100transits to the low-latency mode, the various image processing thatcauses the delay is stopped, so that the processing load regarding theimage processing can be reduced and the delay of projecting the imagecan be suppressed.

Operation 2 When Transition to Low-Latency Mode

Next, the operation 2 of the projector 100 and the PC 200 when atransition instruction to the low-latency mode is output from the PC 200to the projector 100 during projecting the image by the projector 100will be described with reference to FIG. 5 .

In the present embodiment, after receiving the transition instruction tothe low-latency mode from the PC 200, the control of stopping a part orall of the image processing applied to the projector 100 will bedescribed.

In step S501, the control unit 101 receives a low-latency-modetransition instruction from the PC 200 by the image input unit 110. Whenthe control unit 101 detects that the low-latency mode transitioninstruction has been received by interrupting or polling, the processingproceeds to step S502.

In step S502, the control unit 101 determines whether or not a firstprocessing including at least one of a deformation, a rotation, and aninversion is applied to the image projected by the projector 100. Thecontrol unit 101 performs the determination by referring to informationor the like written in the internal memory 115 when the user performssetting regarding a deformation, a rotation and an inversion. As aresult of the determination, when the control unit 101 determines thatat least one of the deformation, the rotation and the inversion isapplied, the processing proceeds to step S503, and when the control unit101 determines that none of the deformation, the rotation and theinversion is applied, the processing proceeds to step S504.

In step S503, the control unit 101 issues an instruction to the imageprocessor 116 to maintain the image processing that is applied among thedeformation, the rotation and the inversion, and to stop the imageprocessing other than the deformation, the rotation and the inversionthat is applied. The image processing other than the deformation, therotation and the inversion that is applied is, for example, processingfor improving image quality such as a super-resolution conversion or anoise reduction that reduces various noises. In step S504, the controlunit 101 issues an instruction to the image processor 116 to stop theimage processing that causes the delay other than the first processingincluding at least one of the deformation, the rotation and theinversion.

In step S505, the control unit 101 receives the video game signal by theimage input unit 110.

The user can arbitrarily change the setting of the informationindicating the display capability stored in the predetermined locationin the EDID of the projector 100. For example, as exemplified in anoperation mode setting window of FIG. 6A, the information indicating thedisplay capability may be rewritten according to the item selected bythe user from the items that can be set as an operation mode of theprojector 100. In addition, when the user selects the low-latencyPRIORITY on the operation mode setting screen of FIG. 6A, the user maybe notified that the setting is not possible while prohibiting anacceptance of setting items regarding a geometric deformation by forexample, rewriting the information indicating the display capability tothe information into the information indicating whether or not thetransition to the low-latency mode is possible or the operation in thelow-latency mode is possible, and graying out the setting regarding thedeformation, the rotation and inversion as exemplified on a geometricdeformation setting screen of FIG. 6B. Additionally, when the processingof either the deformation, the rotation or the inversion is applied tothe projector 100, the information indicating the display capability maybe rewritten into the information indicating that the transition to thelow-latency mode or the operation in the low-latency mode is notpossible.

Further, when the user sets one or more of the deformation, therotation, and the inversion, the user may rewrite the informationindicating the display capability into the information indicating thatthe transition to the low-latency mode or the operation in thelow-latency mode is not possible, so that the PC 200 does not transmitthe low-latency mode transition instruction to the projector 100, andthe control unit 101 may rewrite the information of the EDID andnotifies the PC 200 of the fact that the transition to the low-latencymode or the operation in the low-latency mode is not possible inadvance.

This allows control so that the processing of the deformation, therotation and the inversion is not stopped even in a projector having aspecification that stops all processing of the deformation, the rotationand the inversion in the low-latency mode.

According to the first embodiment, when the projector 100 applies theimage processing of the deformation, the rotation and the inversion whenthe low-latency mode transition instruction is received from the PC 200,the application of these image processing is maintained, and the imageprocessing that cause the delay other than these image processing arestopped. Thus, when the projector 100 transits to the low-latency mode,it is possible to perform an appropriate control to reduce theprocessing load on the image processing, thereby suppressing thedecrease in the viewability of the projection image.

Second Embodiment

Next, the second embodiment will be described.

In the first embodiment, an example has been described in which, whenthe projector 100 receives the transition instruction to the low-latencymode and applies at least one of the deformation, the rotation and theinversion, these image processing are maintained and the imageprocessing other than these image processing that causes the delay isstopped. In contrast, in the second embodiment, the operation of theprojector 100 when the low-latency mode transition instruction isreceived when the deformation amount is relatively small and the levelat which the viewability decreases even if the deformation processing isstopped is low, regarding the deformation processing such as thekeystone correction and the warping correction, will be described.

In the second embodiment, the configuration of the projector 100 and thePC 200 is the same as that of FIG. 2 described in the first embodiment.

FIG. 7 is a flowchart illustrating an operation when the projector 100of the second embodiment receives the low-latency mode transitioninstruction.

In step S701, the control unit 101 receives the transition instructionto the low-latency mode from the PC 200 by the image input unit 110.When the control unit 101 detects that transition instruction to thelow-latency mode has been received by interrupting or polling, theprocessing proceeds to step S702.

In step S702, the control unit 101 determines whether or not thedeformation processing such as the keystone correction or the warpingcorrection is applied to the image projected by the projector 100. Thecontrol unit 101 performs the determination by referring to informationor the like which have been written in the internal memory 115 when thesetting regarding the deformation processing such as the keystonecorrection or the warping correction was performed. As a result of thedetermination, when the control unit 101 determines that the deformationprocessing such as the keystone correction or the warping correction isapplied, the processing proceeds to step S703, and when the control unit101 determines that the deformation processing such as the keystonecorrection or the warping correction is not being applied, theprocessing proceeds to step S705.

In step S703, the control unit 101 determines whether or not the amountof the deformation such as the keystone correction or the warpingcorrection, is equal to or less than a predetermined amount.

FIG. 8A is a diagram exemplifying items that can be set by OSDs foradjusting the deformation amount of the keystone correction. FIG. 8B isa diagram exemplifying items that can be set by OSDs for adjusting thedeformation amounts of the warping correction.

The user can adjust the deformation amount by operating the up, down,left, and right keys of the operation unit 102 or a remote controller(not illustrated) via the OSD. The deformation amount set by the uservia the OSD is written to and held in the internal memory 115.

Here, the determination processing in step S703 will be described as anexample of a condition that the predetermined amount in any one of thekeystone correction setting and the warping correction setting is 3levels or less.

For example, in the keystone correction, the condition of the adjustmentlevel is assumed that all of the four directions on the up, down, left,and right are adjusted to be 3 levels or less, and similarly in thewarping correction, the condition of the adjustment level is assumedthat all of the four directions on the up, down, left, and right areadjusted to be 3 levels or less.

In step S703, the control unit 101 reads the adjustment level set foreach of the keystone correction and the warping correction from theinner memory 115.

As a result of reading the adjustment level, when the control unit 101determines that the deformation amount is equal to or less than thepredetermined amount, the processing proceeds to step S704 and thecontrol unit 101 issues an instruction to the image processor 116 so asto stop the deformation processing of the keystone correction and thewarping correction that have been set.

In step S705, the control unit 101 receives the video game signal fromthe PC 200.

When the control unit 101 determines that the deformation processing isnot being applied in step S702 or the deformation amount is not equal toor less than the predetermined amount in step S703, the processingproceeds to step S705, and the control unit 101 issues an instruction tostop the image processing which causes the low-latency other than thedeformation processing, to the image processor 116.

Note that when the low-latency PRIORITY is selected in the operationmode setting screen of FIG. 6A of the first embodiment, during thedeformation processing is applied in step S702, the deformation amountis determined to be a predetermined amount or less in step S703, thedeformation processing may be controlled to stop.

According to the second embodiment, when the low-latency mode transitioninstruction is received in a case where the deformation amount isrelatively small and the level at which the viewability decreases evenwhen the deformation processing is stopped is low, the deformationprocessing is stopped in the projector 100. Thus, it is possible toperform the appropriate control for reducing the processing load on theimage processing, and to suppress the decrease in the viewability of theprojection image.

Other Embodiments

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully asanon-transitory computer-readable storage medium') to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2020-141103, filed Aug. 24, 2020 which is hereby incorporated byreference herein in its entirety.

What is claimed is:
 1. A projection apparatus comprising: acommunication unit configured to communicate with an external device; animage processor capable of executing a first processing including atleast one of a deformation, a rotation and an inversion, and a secondprocessing other than the first processing, on image signal receivedfrom the external device via the communication unit; a projection unitconfigured to project an image based on the image signal processed bythe image processor; and a control unit configured to switch aprojection operation mode of the projection apparatus to one of aplurality of projection operation modes including a first projectionmode, which is a low-latency projection mode for suppressing a delay indisplaying an image, and a second projection mode, which is not thelow-latency projection mode, wherein the image processor maintains thefirst processing and stops the second processing in response that theprojection operation mode of the projection apparatus is switched to thefirst projection mode from a state in which the projection operationmode of the projection apparatus is the second projection mode and thefirst processing and the second processing are executed.
 2. Theapparatus according to claim 1, wherein the image processor stops imageprocessing that causes a delay other than the first processing inresponse that the projection operation mode of the projection apparatusis switched to the first projection mode from a state in which theprojection operation mode of the projection apparatus is the secondprojection mode and the first processing is not executed.
 3. Theapparatus according to claim 1, wherein the first processing isdeformation processing, and includes at least one of a keystonecorrection and a warping correction.
 4. The apparatus according to claim3, wherein when the projection operation mode of the projectionapparatus is the second projection mode and a deformation amount of thefirst processing is equal to or less than a predetermined amount, theimage processor stops the first processing in response that theprojection operation mode of the projection apparatus is switched to thefirst projection mode.
 5. The apparatus according to claim 1, whereinthe control unit switches of the projection operation mode of theprojection apparatus from the second projection mode to the firstprojection mode in response to a reception of a transition instructionto the low-latency mode from the external device via the communicationunit.
 6. The apparatus according to claim 1, wherein the communicationunit communicates with the external device according to a protocolcomplying with High-Definition Multimedia Interface (HDMI®).
 7. Theapparatus according to claim 1, further comprising a unit configured tochange information indicating a display capability of the projectionapparatus to which the external device refers, wherein when theprojection apparatus starts the projection operation in the secondprojection mode and the first processing is executed, the information ischanged to information indicating that the transition to the low-latencyprojection mode is not possible.
 8. The apparatus according to claim 7,wherein the information is Extended Display Identification Data (EDID)from the information indicating the display capability of the projectionapparatus.
 9. A method of controlling a projection apparatus whichcommunicates with an external device, comprising: executing imageprocessing including a first processing including at least one of adeformation, a rotation and an inversion, and a second image processingother than the first processing, on the image signal received from theexternal device; projecting an image based on the image signal on whichthe image processing has been executed; and switching a projectionoperation mode of the projection apparatus to one of a plurality ofprojection operation modes including a first projection mode, which is alow-latency projection mode for suppressing a delay of an image display,and a second projection mode, which is not the low-latency projectionmode, wherein in the image processing, the first processing ismaintained and the second processing is stopped in response that theprojection operation mode of the projection apparatus is switched to thefirst projection mode from a state in which the projection operationmode of the projection apparatus is the second projection mode and thefirst processing and the second processing are executed.
 10. The methodaccording to claim 9, wherein in the image processing, the imageprocessing that causes a delay other than the first processing isstopped in response that the projection operation mode of the projectionapparatus is switched to the first projection mode from a state in whichthe projection operation mode of the projection apparatus is the secondprojection mode and the first processing is not executed.
 11. The methodaccording to claim 9, wherein the first processing is a deformationprocessing, and includes at least one of a keystone correction and awarping correction.
 12. The method according to claim 11, wherein in theimage processing, when the projection operation mode of the projectionapparatus is the second projection mode and a deformation amount of thefirst processing is equal to or less than a predetermined amount, thefirst processing is stopped in response that the projection operationmode of the projection apparatus is switched to the first projectionmode.
 13. The method according to claim 9, wherein in the controlling,the projection operation mode of the projection apparatus is switchedfrom the second projection mode to the first projection mode in responseto a reception of a transition instruction to the low-latency projectionmode from the external device.
 14. The method according to claim 9,wherein the projection communicates with the external device accordingto a protocol complying with High-Definition Multimedia Interface(HDMI®).
 15. The method according to claim 9, further comprisingchanging information indicating a display capability of the projectionapparatus to which the external device refers, wherein when theprojection apparatus starts the projection operation in the secondprojection mode and the first processing is executed, the information ischanged to information indicating that the transition to the low-latencyprojection mode is not possible.
 16. The method according to claim 15,wherein the information is Extended Display Identification Data (EDID)from the information indicating the display capability of the projectionapparatus.
 17. A non-transitory computer-readable storage medium storinga program that causes a computer to execute a method of controlling aprojection apparatus which communicates with an external device,comprising: executing image processing including a first processingincluding at least one of a deformation, a rotation and an inversion,and a second image processing other than the first processing, on theimage signal received from the external device; projecting an imagebased on the image signal on which the image processing has beenexecuted; and switching a projection operation mode of the projectionapparatus to one of a plurality of projection operation modes includinga first projection mode, which is a low-latency projection mode forsuppressing a delay of an image display, and a second projection mode,which is not the low-latency projection mode, wherein in the imageprocessing, the first processing is maintained and the second processingis stopped in response that the projection operation mode of theprojection apparatus is switched to the first projection mode from astate in which the projection operation mode of the projection apparatusis the second projection mode and the first processing and the secondprocessing are executed.